Beyond what is due, usual, expected, or necessary; additional; supernumerary; also, extraordinarily good; superior; as, extra work; extra pay. H. Spencer. [1913 Webster]

1.  Something in addition to what is due, expected, or customary; esp., an added charge or fee, or something for which an additional charge is made; as, at some hotels air conditioning is an extra. [Webster 1913 Suppl.]

2.  An edition of a newspaper issued at a time other than the regular one. [Webster 1913 Suppl.]

3.  A run, as from a bye, credited to the general score but not made from a hit. [Webster 1913 Suppl.]

4.  Something of an extra quality or grade. [Webster 1913 Suppl.]

extra, adj., adv., & n.
--adj. additional; more than is usual or necessary or expected.
--adv.
1 more than usually.
2 additionally (was charged extra).
--n.
1 an extra thing.
2 a thing for which an extra charge is made.
3 a person engaged temporarily to fill out a scene in a film or play, esp. as one of a crowd.
4 a special issue of a newspaper etc.
5 Cricket a run scored other than from a hit with the bat.

Idiom:
extra cover Cricket
1 a fielding position on a line between cover-point and mid-off, but beyond these.
2 a fielder at this position. extra size outsize. extra time Sport a further period of play at the end of a match when the scores are equal.

Etymology:
prob. a shortening of EXTRAORDINARY

N  the drama, the stage, the theater, the play, film the film, movies, motion pictures, cinema, cinematography, theatricals, dramaturgy, histrionic art, buskin, sock, cothurnus, Melpomene and Thalia, Thespis, play, drama, stage play, piece, five-act play, tragedy, comedy, opera, vaudeville, comedietta, lever de rideau, interlude, afterpiece, exode, farce, divertissement, extravaganza, burletta, harlequinade, pantomime, burlesque, opera bouffe, ballet, spectacle, masque, drame comedie drame, melodrama, melodrame, comidie larmoyante, sensation drama, tragicomedy, farcical-comedy, monodrame monologue, duologue trilogy, charade, proverbs, mystery, miracle play, musical, musical comedy, western, horse opera, flick, spy film, love story, adventure film, documentary, nature film, pornographic film, smoker, skin flick, X-rated film, act, scene, tableau, induction, introduction, prologue, epilogue, libretto, performance, representation, mise en scene, stagery, jeu de theatre, acting, gesture, impersonation, stage business, gag, buffoonery, light comedy, genteel comedy, low comedy, theater, playhouse, opera house, house, music hall, amphitheater, circus, hippodrome, theater in the round, puppet show, fantoccini, marionettes, Punch and Judy, auditory, auditorium, front of the house, stalls, boxes, pit, gallery, parquet, greenroom, coulisses, flat, drop, drop scene, wing, screen, side scene, transformation scene, curtain, act drop, proscenium, stage, scene, scenery, the boards, trap, mezzanine floor, flies, floats, footlights, offstage, orchestra, theatrical costume, theatrical properties, movie studio, back lot, on location, part, role, character, dramatis personae, repertoire, actor, thespian, player, method actor, stage player, strolling player, stager, performer, mime, mimer, artists, comedian, tragedian, tragedienne, Roscius, star, movie star, star of stage and screen, superstar, idol, sex symbol, supporting actor, supporting cast, ham, hamfatter, masker, pantomimist, clown harlequin, buffo, buffoon, farceur, grimacer, pantaloon, columbine, punchinello, pulcinello, pulcinella, extra, bit- player, walk-on role, cameo appearance, mute, figurante, general utility, super, supernumerary, company, first tragedian, prima donna, protagonist, jeune premier, debutant, debutante, light comedian, genteel comedian, low comedian, walking gentleman, amoroso, heavy father, ingenue, jeune veuve, mummer, guiser, guisard, gysart, masque, mountebank, Jack Pudding, tumbler, posture master, acrobat, contortionist, ballet dancer, ballet girl, chorus singer, coryphee danseuse, property man, costumier, machinist, prompter, call boy, manager, director, stage manager, acting manager, producer, entrepreneur, impresario, backer, investor, angel, dramatic author, dramatic writer, play writer, playwright, dramatist, mimographer, dramatic, theatric, theatrical, scenic, histrionic, comic, tragic, buskined, farcical, tragicomic, melodramatic, operatic, stagy, on the stage, on the boards, on film, before the floats, before an audience, behind the scenes, fere totus mundus exercet histrionem, suit the action to the word, the word to the action, the play's the thing, to wake the soul by tender strokes of art.

N  redundancy, redundance, too much, too many, superabundance, superfluity, superfluence, saturation, nimiety, transcendency, exuberance, profuseness, profusion, repletion, enough in all conscience, satis superque, lion's share, more than enough, plethora, engorgement, congestion, load, surfeit, sickener, turgescence, overdose, overmeasure, oversupply, overflow, inundation, avalanche, accumulation, heap, drug, drug in the market, glut, crowd, burden, excess, surplus, overplus, epact, margin, remainder, duplicate, surplusage, expletive, work of supererogation, bonus, bonanza, luxury, intemperance, extravagance, exorbitance, lavishment, pleonasm, too many irons in the fire, embarras de richesses, redundant, too much, too many, exuberant, inordinate, superabundant, excessive, overmuch, replete, profuse, lavish, prodigal, exorbitant, overweening, extravagant, overcharged, supersaturated, drenched, overflowing, running over, running to waste, running down, crammed to overflowing, filled to overflowing, gorged, ready to burst, dropsical, turgid, plethoric, obese, superfluous, unnecessary, needless, supervacaneous, uncalled for, to spare, in excess, over and above, de trop, adscititious, supernumerary, on one's hands, spare, duplicate, supererogatory, expletive, un peu fort, over, too, over and above, overmuch, too much, too far, without measure, beyond measure, out of measure, with a to spare, over head and ears, up to one's eyes, up to one's ears, extra, beyond the mark, acervatim, it never rains but it pours, fortuna multis dat nimium nulli satis, Degree of Subservience.

N  addition, annexation, adjection, junction, superposition, superaddition, superjunction, superfetation, accession, reinforcement, increase, increment, supplement, accompaniment, interposition, insertion, added, additional, supplemental, supplementary, suppletory, subjunctive, adjectitious, adscititious, ascititious, additive, extra, accessory, au reste, in addition, more, plus, extra, and, also, likewise, too, furthermore, further, item, and also, and eke, else, besides, to boot, et cetera, and so on, and so forth, into the bargain, cum multis aliis, over and above, moreover, with, withal, including, inclusive, as well as, not to mention, let alone, together with, along with, coupled with, in conjunction with, conjointly, jointly, adde parvum parvo magnus acervus erit, addition, annexation, adjection, junction, superposition, superaddition, superjunction, superfetation, accession, reinforcement, increase, increment, supplement, accompaniment, interposition, insertion, added, additional, supplemental, supplementary, suppletory, subjunctive, adjectitious, adscititious, ascititious, additive, extra, accessory, au reste, in addition, more, plus, extra, and, also, likewise, too, furthermore, further, item, and also, and eke, else, besides, to boot, et cetera, and so on, and so forth, into the bargain, cum multis aliis, over and above, moreover, with, withal, including, inclusive, as well as, not to mention, let alone, together with, along with, coupled with, in conjunction with, conjointly, jointly, adde parvum parvo magnus acervus erit.